Five Star Rating Calculator
Enter how many 1, 2, 3, 4 and 5-star reviews a product or service has received and instantly get the weighted average rating, Bayesian average (which stabilises scores with few reviews), the positive review percentage and the full distribution breakdown.
Weighted average out of 5 stars across all reviews
- 1
Weighted sum
5×120 + 4×85 + 3×30 + 2×12 + 1×8 = 1,062 - 2
Total reviews
120 + 85 + 30 + 12 + 8 = 255 - 3
Average rating
1,062 ÷ 255 = 4.16
How does this calculator work?
Average star rating = (5n₅ + 4n₄ + 3n₃ + 2n₂ + n₁) / N. Bayesian average = (25×3 + weighted sum) / (25 + N) to stabilise small counts. Positive rate = (n₄+n₅)/N×100. Enter the count of 1–5 star reviews to get all three scores plus the distribution breakdown.
Formula
How this is calculated
The weighted average star rating multiplies each star value (1–5) by its review count, sums the results, and divides by the total number of reviews. This gives the intuitive "average stars out of 5" figure shown on most platforms: Average = (5·n₅ + 4·n₄ + 3·n₃ + 2·n₂ + 1·n₁) / N.
The Bayesian average shrinks extreme scores toward a prior mean when the review count is small. The formula is (C·m + Σwᵢ·nᵢ) / (C + N), where m = 3.0 (a neutral prior mean) and C = 25 (a prior "virtual" review count). A product with 2 reviews averaging 5.0 gets a Bayesian score close to 3.0, while one with 2,000 reviews converges toward its true average. This prevents new products with a single glowing review from topping leaderboards.
The satisfaction score is the percentage of 5-star reviews minus the percentage of 1- and 2-star reviews, analogous to a net promoter logic for review data. Positive rate counts 4- and 5-star reviews as a proportion of all reviews.
Frequently asked questions
The Bayesian average adds a set of "imaginary" neutral reviews (C = 25 at rating 3.0) to stabilise the score when the real review count is low. As more real reviews accumulate the effect fades and the Bayesian average converges to the plain average. This makes comparisons fairer between products with very different review counts.
It is the percentage of 5-star reviews minus the percentage of 1- and 2-star reviews, giving a single number from −100% (all negative) to +100% (all positive). A score above 0% means more promoters than detractors by percentage.
This calculator is designed for 1–5 star systems. For a 1–10 scale or thumbs up/down system, the formula structure is the same but the weights change — adapt accordingly in a spreadsheet.
TG we-Calculate Editorial Team. (2026). Five Star Rating Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/five-star-rating-calculator
TG we-Calculate Editorial Team. "Five Star Rating Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/five-star-rating-calculator.
TG we-Calculate Editorial Team, "Five Star Rating Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/five-star-rating-calculator
@misc{wecalculate_five_star_rating_calculator, title = {Five Star Rating Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/five-star-rating-calculator}}, year = {2026}, note = {TG we-Calculate} }
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